Here's Why Dogs Sniff Your Crotch When You're On Your Period

It’s a well-known fact that dogs don’t always have the strongest sense of boundaries. These are creatures that like to lick strangers’ faces and sniff their crotches, after all.

The latter behavior can lead to some awkward moments for menstruating women, many of whom have reported feeling like they attract extra attention from dogs during their time of the month.

So why does it seem like dogs get extra sniff-happy around women on their periods? HuffPost spoke to a couple of experts to find out.

The Truth About Sniff-Happy Dogs

“Dogs are scent-driven creatures,” said Kate Mornement, an Australian animal behaviorist and consultant. “They experience their world predominantly through their sense of smell. When a woman is on her period she probably just smells different, which is interesting to the dog.”

The canine sense of smell is so powerful that dogs are famously employed in drug-sniffing operations, forensic investigations and bed bug detection. There are about 300 million sense receptors in their noses, versus the 5 million in human noses. Studies have also shown dogs to be effective at detecting health conditions like cancer and migraines.

“When dogs sniff each other’s butts or when they’re sniffing a woman’s crotch while she’s on her period, it’s an information-seeking session,” Kirstin McMillan, a third-generation animal trainer based in Los Angeles, explained. “When a woman is menstruating, I’m sure there are pheromones coming off.”

Looking at it biologically, dogs have a special sensory receptor called the vomeronasal organ, or the Jacobson’s organ. In humans and other mammals, apocrine glands secrete pheromones, which can relay a lot of information to dogs. These glands are highly concentrated in the groin areas in humans, so dogs are drawn to these regions of our bodies in their scent-based information-gathering sessions. This is also why dogs sniff each others’ genital and anal areas as a greeting.

“A lot of times it’s about sex,” said McMillan. “They may be smelling for the presence of testosterone. Intact male dogs are often more aggressive and territorial, so they’re more likely to get really into it ― because they’re trying to check for testosterone to determine the presence of some sort of challenge that needs to be posed or threat that they are under.”

Jean Louis Aubert via Getty Images

Dogs sniff each other's genital and anal regions as a way to gather information.

Intact (i.e. not neutered) male dogs may sniff female dogs to detect information about their reproductive status and then may mount them, depending on what they find, McMillan added. And female dogs greeting other female dogs may also be smelling to seek information about their fertility to find out if they pose a threat.

“Imagine a young woman in her childbearing years. In some ways, that poses a threat to another woman,” McMillan said. “As humans, we just pretend we don’t care, but dogs actually do. They’re not pretending.”

Which Dogs Are More Likely To Do It

While a dog sniffing a menstruating human woman’s crotch may not involve quite the same threat-detection or sex-information-seeking, there’s still a level of interest.

“Even on set, you’ll find this when you’re working with a dog,” said McMillan. “If the talent is menstruating, the dog will definitely know and be a little bit more interested.”

Mornement told HuffPost that medium to large dogs are more likely to be “opportunistic crotch-sniffers,” meaning that they might take a sniff if their nose happens to be in the vicinity of a woman on her period. “It’s not as easy for smaller dogs to stick their nose where it doesn’t belong, unless you’re sitting on the floor,” she said.

Scent hounds like bloodhounds and basset hounds have a stronger sense of smell than other kinds of dogs, so they are more likely to take interest in a menstruating woman’s groin area, McMillan noted. But it mostly comes down to how well a dog is trained.

“Some dogs have been trained to do greetings more politely and have just done more greetings, so regardless of what they’re detecting, they’re going to seem like they don’t care,” she explained. “But they can still smell that you’re on your period. They’ve just been conditioned to be indifferent. Other dogs are more obnoxious and just really shove their noses in the crotch and take a good inhale.”

Mornement offered advice for dealing with the “obnoxious” sort of dog.

“If your dog is a crotch sniffer and you’re embarrassed by it, teach them an incompatible behavior, such as sitting calmly,” she said. “Use treats to reward your dog for sitting when other people are nearby.”

The Tampon Issue...

A related issue is the attraction many dogs seem to feel toward used tampons in trash cans.

“I feel like all of us have a story about that, like when company came over, and Rex had his way with our tampons.” said McMillan. “They’ll be partying with your tampon, chewing it up piece by piece, and that really changes your relationship to your dog. It’s so gross. They’re very attracted to that scent, and it’s actually dangerous.”

If a dog swallows a tampon, it can cause a potentially fatal blockage ― particularly if the tampon hasn’t been torn apart first. In this scenario, it’s best to try to induce vomiting and call your vet immediately.

“You may end up having to take them in because it might be something that doesn’t pass. Or if the tampon string is long enough, it can get entangled in the intestines,” McMillan explained, adding that the chemicals in many standard tampons may not be great for dogs either.

The easiest way to avoid this scenario is to use lidded trash cans, though that may not be enough. “If you have a Houdini, you need a locked lidded trash can, but it’s not that big of a deal.”

Ultimately, McMillan sees the period crotch-sniffing as a small side effect of the amazing power of canine scent.

“It might work against you in public settings when you have a bloodhound giving you a virtual pap smear,” she said. “But when you are getting screened for cancer, you’re really appreciating that bloodhound and the accuracy of their nose.”